1. Field of the Invention
The present invention relates to a two-chamber type combined container-syringe, in which a medicinal solution is previously filled and stored, and the can be taken out from a package upon use and instantly used.
Priority is claimed on Japanese Patent Application No. 2013-28315, filed Feb. 15, 2013, the content of which is incorporated herein by reference.
2. Description of Related Art
A combined container-syringe, since a medicinal solution is previously filled, can be taken out from a package to be instantly used in a medical institute without complicated operation. The combined container-syringe is widely employed in many hospitals and clinics due to good convenience and large contribution to reduction in work of health care providers such as doctors, nurses, and so on.
Conventionally, a two-chamber type combined container-syringe in which a preparation and solution are separately filled is known as a kind of the combined container-syringe (for example, refer to Japanese Patent No. 1759157).
In the two-chamber type combined container-syringe, a front stopper is fitted into a distal end side of an outer tube and an end stopper is fitted into a rear end side, and the inside of the outer tube is divided into two front and rear chambers by a middle stopper fitted into a central section of the outer tube. In addition, a bypass groove is formed at a portion of the outer tube closer to the distal end side than the middle stopper such that a portion of an inner circumferential surface of the outer tube swells outward. Further, a powdered preparation is sealed in the front chamber of the distal end side of the middle stopper, and the distal end is sealed by the front stopper. Meanwhile, solution is sealed in the rear chamber of the rear end side of the middle stopper, and the rear end is sealed by the end stopper. In addition, a plunger rod is connected to the rear end of the end stopper.
When the two-chamber type combined container-syringe having the above-mentioned configuration is used, the end stopper is advanced in the outer tube by pushing the plunger rod into the outer tube. Then, as a pressing force is applied to the middle stopper via the solution by advancement of the end stopper, the middle stopper is also advanced with the advancement of the end stopper. Then, when the middle stopper arrives at the bypass groove, the front and rear chambers of the middle stopper come in communication with each other via a swelling portion of the bypass groove. Accordingly, the solution in the rear chamber flows into the front chamber, and an injection drug is prepared by mixing the solution and the preparation of the front chamber.
Here, for example, in Japanese Patent No. 2942835, the combined container-syringe in which the plurality of above-mentioned bypass grooves are formed in an axial direction of an outer tube is disclosed.
That is, in Japanese Patent No. 2942835, the combined container-syringe in which a plurality of bypass grooves are formed in an inner circumferential surface of the outer tube to continue through the entire region thereof in a circumferential direction is disclosed. In addition, in this document, the combined container-syringe in which a portion between the bypass grooves neighboring in the circumferential direction protrudes toward an inner diameter side of the outer tube more than an inner circumferential surface of the outer tube is also disclosed.
Furthermore, in the specification of U.S. Pat. No. 2,591,046, the combined container-syringe in which a plurality of bypass grooves are formed in an inner circumferential surface of an outer tube at intervals in a circumferential direction is disclosed. In this combined container-syringe, the bypass groove has a rectangular cross-sectional shape along a direction perpendicular to an axis of the outer tube, and the depth of the bypass groove from the inner circumferential surface of the outer tube is set to be near the outer circumferential surface of the outer tube.
In the above-mentioned two-chamber type combined container-syringe, in order to appropriately mix the solution and the preparation, the middle stopper must be stay at a region in the outer tube at which the bypass groove is present, until flowing of all of the solution of the rear chamber into the front chamber is terminated. Furthermore, depending on a kind of the preparation filled in the front chamber, all of the solution of the rear chamber must be rapidly flow into the front chamber.
However, when a cross-sectional area of the bypass groove is too small, even when the plunger rod is further pushed in a state in which the middle stopper arrives at the bypass groove, since flow resistance of the solution passing through the bypass groove is large, the solution may not smoothly flow through the bypass groove. Accordingly, the pressing force applied to the solution via the end stopper by pushing of the plunger rod mainly contributes to the advancement of the middle stopper. As a result, even when the solution remains at the rear end of the middle stopper, the middle stopper may advance over the bypass groove.
On the other hand, when a total cross-sectional area of the plurality of bypass grooves is increased, while the flowing of the solution in the bypass groove can be accelerated, the amount of the solution remaining in the bypass groove may be increased and the strength of the outer tube may be decreased if the cross-sectional area is too large.
In consideration of the above-mentioned problems, the present invention is directed to provide a two-chamber type combined container-syringe capable of causing solution to smoothly flow through a bypass groove, reducing an amount of the solution remaining in the bypass groove, and enabling smooth sliding of a middle stopper and an end stopper without to decrease slidability of these stoppers due to the bypass.